notes

"The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or ill. The verb to afford is found in the dictionary, but the noun affordance is not. I have made it up. I mean by it something that refers to both the environment and the animal in a way that no existing term does. It implies the complementarity of the animal and the environment...

"If a terrestrial surface is nearly horizontal (instead of slanted), nearly flat (instead of convex or concave), and sufficiently extended (relative to the size of the animal) and if its substance is rigid (relative to the weight of the animal), then the surface affords support...

"Note that the four properties listed --- horizontal, flat, extended, and rigid --- would be physical properties of a surface if they were measured with the scales and standard units used in physics. As an affordance of support for a species of animal, however, they have to be measured relative to the animal. They are unique for that animal. They are not just abstract physical properties."

II.

Norman, Donald. The Design of Everyday Things, (p. 9):

"When used in this sense, the term affordance refers to the perceived and actual properties of the thing, primarily those fundamental properties that determine just how the thing could possibly be used. A chair affords ("is for") support, and, therefore, affords sitting."

"An affordance is a relationship between an object in the world and the intentions, perceptions, and capabilities of a person. The side of a door that only pushes out affords this action by offering a flat pushplate. The idea of affordance, powerful as it is, tends to describe the surface of a design. For us the term "affordance" does not reach far enough into the periphery where a design must be attuned to but not attended to."

"A chance encounter is the dynamic interaction of a user with a node of information when no a priori intentions initiated the exploration. It occurs at the point in the interaction when a human makes an accidental discovery, especially one that is tightly coupled with sagacity. It is often concomitant on the user's prior knowledge and the user's recognition of the 'affordances' (Gibson, 1977) in the text (Toms, 1997). 'Affordances' are a characteristic of an object which makes it obvious how that object will be used (Norman, 1988). Toms (1997) suggested that, like any interface object, text has 'affordances' which are activated when a user interacts with the text and are directly influenced by a person's perspective at that point in time. Likely chance encounters are triggered when the 'affordances' of the text are recognized by the user."

"Gibson felt that artificial laboratory situations had misled psychologists into conceptualizing perception as a physically passive, internal, cerebral event. He believed that new researchers studying perception should not construct artificially isolated and static experiemental conditions that have nothing to do with everyday life--instead they should strive to approximate natural conditions. If they did so they would come to understand the senses not as passive mechanisms receiving valueless data but as active, exploratory systems attuned to dynamic meanings already there in the environment. These dynamic meanings, or "affordances" as Gibson has called them, are the way specific regions of the environment directly address themselves to particular species or individuals. Thus, to a human maple tree may afford "looking at" or "sitting under," while to a sparrow it affords "perching," and to a squirrel it affords "climbing." But these values are not found inside the minds of the animals. Rather they are dynamic, addressive properties of the physical landscape itself when the landsacpe is comprehended in a manner that does not artificially separate it from the life of the various organisms that inhabit it and contribute to its continuing evolution."

"We will use the term lifeworld to mean an environment described in terms of the customary ways of structuring the activities that take place within it -- the conventional uses of tools and materials, the ``loop invariants'' that are maintained within it by conventional activities, and so on. The term originally comes from phenomenological sociology [36], where it refers to the familiar world of everyday life, and specifically to that world as described in the terms that make a difference for a given way of life. Cats and people, for example, can be understood as inhabiting the same physical environment but different lifeworlds. Kitchen cupboards, window sills, and the spaces underneath chairs have different significances for cats and people, as do balls of yarn, upholstery, television sets, and other cats. Similarly, a kitchen affords a different kind of lifeworld to a chef than to a mechanic, though clearly these two lifeworlds may overlap in some ways as well. A lifeworld, then, is not just a physical environment, but the patterned ways in which a physical environment is functionally meaningful within some activity.

"This idea is similar to Gibson's theory of perception [14], but the two theories also differ in important ways. Whereas Gibson believes that the perception of worldly affordances is direct, we believe that the perceptual process can be explained in causal terms. Also, whereas Gibson treated the categories of perception as essentially biological and innate, we regard them as cultural and emergent."

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